package sliding_window;

import java.util.*;

public class findSubstring {
    public List<Integer> findSubstring(String s, String[] words) {
        List<Integer> ret = new ArrayList<>();

        Map<String,Integer> hash1 = new HashMap<String,Integer>();
        for(String x : words){
            hash1.put(x,hash1.getOrDefault(x,0)+1);
        }

        int len = words[0].length(),m = words.length;
        for(int i = 0; i < len;i++) {
            int count = 0;
            Map<String,Integer> hash2 = new HashMap<String,Integer>();
            for(int left = i,right = i ;right+len <= s.length();right+=len){
                //进窗口+维护count
                String in = s.substring(right,right+len);
                hash2.put(in,hash2.getOrDefault(in,0)+1);
                if(hash2.get(in) <= hash1.getOrDefault(in,0)) {
                    count++;
                }
                //判断
                if(right - left+1 > len*m){
                    String out = s.substring(left,left+len);
                    if(hash2.get(out) <= hash1.getOrDefault(out,0)) {//维护count
                        count--;
                    }
                    hash2.put(out,hash2.get(out)-1);//出窗口
                    left += len;
                }
                if(count == m) {
                    ret.add(left);
                }
            }
        }
        return ret;
    }
}
